The present invention relates to an arrangement for connecting structural members.
More particularly this invention relates to an arrangement for connecting horizontal and vertical members of a structure, such as a scaffold or the like.
It is known in the art that single tubular horizontal members of a frame or scaffold have comparatively low breaking strength, which is especially true in cases of long span-length members. Therefore, it has been suggested to provide the horizontal members of a frame with two tubular elements which are spaced from one another by a certan distance. In this case two elements are connected to each other by intermediate distance members, which extend from one horizontal element to another either normally or diagonally relative to these horizontal elements, thus defining so-called "frame girders" or "braced girders." Such girders can reliably bridge considerable span distances. The upper horizontal element and the middle portion of the lower horizontal element are parallel to each other. The end portions of the lower horizontal element are bent upwardly towards and into engagement with the upper horizontal element. However, it is also possible to arrange the lower horizontal element entirely parallel to the upper horizontal element. It is advantageous to provide the lower horizontal element with the strength equal that of the upper horizontal element, regardless of the fact that the lower element does not have the direct contact with a load applied on such a girder and therefore it may have strength smaller than that of the upper element.
An especially disadvantageous feature of such frame or braced girders resides in the fact that the horizontal elements are connected to corresponding vertical elements by angular-coupling members. Due to such a connection a certain unreliability arises concerning carrying capacity of such a frame. The clamping effect of such a coupling member depends primarily on reliability of the screw connection of the coupling member to the horizontal and vertical elements. Furthermore, the angular-coupling member is a relatively complicated device, because a carrier of such a coupling member has to be located laterally and eccentrically on both horizontal and vertical members. Therefore, a location of the coupling member on the horizontal and vertical elements has to be measured and designated before installing the coupling member. Obviously, such a preliminary measure is a relatively time-consuming operation.